The present invention relates to a breather chamber structure of an internal combustion engine.
An internal combustion engine has a blow-by gas return apparatus for returning blow-by gas leaking in a crank chamber at a compression stroke to a suction system to prevent the blow-gas from being discharged to the atmosphere. The blow-by gas return apparatus includes a breather chamber for separating gas and liquid each other. Oil separated in the breather chamber is taken out and the blow-by gas including remaining not separated oil is sent to the suction system to be burned again.
A breather chamber disposed on a side wall of a cylinder block is disclosed in Japanese Laid-Open Patent Publication Hei 4-342864.
This breather chamber is provided on the cylinder block side wall utilizing a relatively large space formedbetween the cylinder block and a surge tank.
When the engine runs normally, the breather chamber is warmed by heat of the cylinder block so that interior of the breather chamber is not dewed, but in course of warming-up immediately after starting of the engine, especially in the cold season, the breather chamber is not warmed soon so that vapor in the blow-by gas condenses within the breather chamber and it is feared that the condensed water is mixed in the separated oil to be recovered.
The water mixed in the oil hasten deterioration of oil and causes generation of sludge varnish.
In the above-mentioned publication, the breather chamber is formed by covering a breather hollow on the cylinder block side wall with a lid plate, or the breather chamber is formed integrally with the cylinder block side wall, or a side wall of the surge tank is used as the lid plate. However, the breather chamber formed by covering with the lid plate requires many parts, the breather chamber formed integrally with the cylinder block side wall is complicated in working and forming, and the breather chamber using the side wall of the surge tank as the lid plate is troublesome in assembling work and injures universality of the surge tank.
The present invention has been accomplished in view of the foregoing, and an object of the invention is to provide a breather chamber structure of an internal combustion engine in which condensation of vapor within the breather chamber is prevented, the number of required parts is small, the space efficiency is superior and enlargement of the whole engine can be avoided.
In order to achieve the above object, the present invention provides a breather chamber structure of an internal combustion engine having auxiliary machinery attached to a side wall of a cylinder block by means of an auxiliary machinery bracket, comprising a breather chamber formed by the side wall of the cylinder block and the auxiliary machinery bracket between the side wall and the bracket, and a cooling water passage formed on at least one of the side wall of the cylinder block and the auxiliary machinery bracket swelling in the breather chamber.
On warming-up immediately after starting of the engine when temperature of the breather chamber is very low, the breather chamber can be warmed easily by circulating cooling water through the cooling water passage to prevent condensation of vapor in the breather chamber and it can be avoided that water is mixed in recovered oil.
When the engine is in warming-up operation, the breather chamber can be warmed quickly by letting cooling water warmed by the engine flow through the cooling water passage swelling in the breather chamber and condensation of vapor in the breather chamber can be prevented easily.
Since the breather chamber is formed between the auxiliary machinery bracket and the cylinder block side wall utilizing the auxiliary machinery bracket, and the cooling water passage is provided in the breather chamber, a space between the cylinder block and the auxiliary machinery is utilized to improve space efficiency, enlarging of the whole engine can be avoided, the number of parts can be reduced and the assembling work can be facilitated.
According to the invention. In the breather chamber structure of an internal combustion engine having auxiliary machinery attached to a side wall of a cylinder block by means of an auxiliary machinery bracket, a breather chamber formed by the side wall of the cylinder block and the auxiliary machinery bracket between the side wall and the bracket, and a cooling water passage formed on at least one of the side wall of the cylinder block and the auxiliary machinery bracket swelling in the breather chamber, the cooling water passage may be formed on the auxiliary machinery bracket, and a water pump may be attached to the auxiliary machinery bracket for circulating cooling water through the cooling water passage. Since the auxiliary machinery bracket constituting the breather chamber is utilized to attach the water pump, the cooling water passage can be formed in the breather chamber easily, the number of parts can be reduced and assembling can be carried out easily.
According to the invention, in the breather chamber structure having the cooling water passage formed on the auxiliary machinery bracket and the water pump attached to the auxiliary machinery bracket for circulating cooling water through the cooling water passage, a suction side cooling water passage connected to a suction side of the water pump and a discharge side cooling water passage connected to a discharge side of the water pump may be formed on a breather chamber portion of the auxiliary machinery bracket. Since both the suction side cooling water passage and the discharge side cooling water passage are formed in the breather chamber, the breather chamber can be warmed efficiently to prevent condensation of vapor when the engine is started.
In the breather chamber structure, a blow-by gas passage connecting an interior of a crankcase with the breather chamber may be formed in the side wall of the cylinder block, and an oil recovery passage for recovering oil separated from the blow-by gas in the breather chamber into an oil pan may be formed in a lower part of the side wall of the cylinder block. Since both the blow-by gas passage and the oil recovering passage are formed in the side wall of the cylinder block, it is unnecessary that such passages communicating with the interior of the crankcase and the interior of the oil pan are formed in the auxiliary machinery bracket to bring out a complicated construction and an attachment for sealing. Therefore, the construction can be simplified and the cost can be lowered.
In the breather chamber structure, the auxiliary machinery bracket may be a synthetic bracket for attaching more than two auxiliary machines. A plurality of auxiliary machines can be attached intensively with a few parts, enlarging of the whole engine can be prevented, the assembling work is easy and the cost can be reduced.